Tube and plate connection



May 19, 1959 A, HUET 2,88 ,881

TUBE. AND PLATE CONNECTION VENTOR A RE HUET Filed March 5, 1957 UnitedStates Patent TUBE AND PLATE CONNECTION Andr Huet, Paris, France,assignor to Combustion Engineering, Inc., New York, N.Y., a corporationof Delaware Application March 5, 1957, Serial No. 644,075 2 Claims. (Cl.29-1575) The present invention relates to heat exchangers; in particularto improvements in a tubular type exchanger. The plates which seal offthe ends of such heat exchangers are pierced with circular holes inwhich the ends of the tubes constituting the tube bank of the exchangerare seated and fastened, generally by tube expanding.

It is possible to replace the holes cut in the plates by nozzle-likenecks to constitute tube connections, these being produced, forinstance, by punching the tubular plate, the said neck providing aroundeach opening a boss, or rim, to which the tube is connected.

Practice has shown that it would be of importance to be able to obtainon the tube plates connections having double bosses, i.e. tubeconnections providing a neck, or boss on both sides of the tube plate.The tube to be fastened can then eventually pass through the tubularplate in which it is maintained, for instance, by hot shrinking, andwelding of the ends of the double necks to the circumference of thetube.

Applicant has conceived a method for the manufacture of theseconnections, or double boss necks constituting the object of thisinvention as well as an improved tube plate provided with necks.

According to this invention, the tube plate is first pierced by means ofa punch to create an ordinary unilateral tubular neck projecting fromthe tube plate from the pierced tube hole. Preferably this neck shouldhave a high rim and be of conical, rather than pointed shape, i.e. thatit shows at the top a relatively small end face; or even none, the outerwall of the neck merging with the inner wall at the end.

In the course of a second step of the method the tubular neck producedon one side of the plate is opened out in such manner that the diameterof the neck at its extremity becomes larger than that at its base, i.e.that of the opening formed in the plate. In the course of a thirdoperation, by passing a punch of larger diameter than the tube hole inthe opposite direction to that of the first operation, the bore of thewidened neck is restored to a circular shape while the punch displacespart of the plate wall around the opening and causes a protrusion on theside opposite to that where the first neck was produced which producesan accumulation of metal which constitutes a second neck on the otherside of the plate (having eventually the same diameter), and finally acylindrical or non-cylindrical nozzle with double rims is obtained.

The following description when read in connection with the accompanyingdrawing will help to understand the manner in which the invention can beexecuted.

Figure 1 shows in cross section a tube plate on which a neck-like bosshas been formed around a tube hole in accordance with the first step ofthe inventive method.

Figure 2 shows the neck of Figure 1 after being widened at itsextremity.

Figure 3 shows in cross section the neck of Figure 2 ice As shown in thedrawings, in order to obtain a double necked connection in accordancewith this invention, one starts by forming on the tube plate 10 atubular neck 12, for instance by pushing a punch in the direction ofarrow A through the preheated plate, in cooperation with a die appliedfrom the other side of the plate. A rather.

high neck 12 with relatively flat rims or end face 14 is thus obtained.

In the course of a second operation, the neck 12 of Figure 1, shown indotted line in Figure 2,, is opened or widened at its extremities, i.e.so that its rim 14 is spread so as to form a divergent cone 16, as shownin straight line in Figure 2, the circular opening 20 at the rim 14attaining a diameter larger than that of the opening 22 pierced in plate10. This operation can be executed in different ways. For instance,after heating the neck 12 a mandrel can be pivoted inside thisprotuberance in order to obtain its gradual widening by generating aconical surface.

In the course of a third operation, after the conical neck 16 has beensuitably heated, especially in region D where it merges into plate 10, apunch 24 is pushed into the widened neck 16 in the direction B oppositeto that of the punch which carried out the first operation to form theneck 12. The punch 24, as can be seen in Figure 3, is of a diameterlarger than opening 22 but less than the diameter 20 of the extremity ofthe neck and hits the neck near circumference C and, in its drivingmovement displaces and carries along with it the metal of region D ofthe plate 10, which stretches out and forms, on the other side of thetube plate, a boss or neck 30 as shown in Figure 4.

Figure 4 shows in dotted line neck 16 before the final punchingoperation. It can be seen, that during the final operation the wall ofthe widened neck 16 folds back along punch 24, while the metal of regionD of the neck and plate is constituting neck 30. In the course of thisthird operation, punch 24 can act in cooperation with a die 32 appliedfrom the other side of tube plate 10, and which keeps the metal of tubeplate 10 in the required position so as to obtain finally the doublenecked connection 30, 34 with cylindrical opening (Fig. 5).

In order to fasten a tube in the double necked connection thus obtained,one begins with heating necks 30, 34 and then introduces the cold tube36 into the opening. During the cooling off period as the necks 30, 34shrink a strong binding effect of tube 36 in necks 30, 34 takes place.The fastening can be completed by two seam welds 38 between plate 10 andthe necks 30, 34 at their extremities.

As a variant, for fastening tube 36 in the double necked connection, theend faces or rims 40 of the necks 30, 34 can be pinched by outsidepressure, so as to decrease the inlet openings of the connection fromboth sides, and to obtain in cross section a kind of bracket, as can beseen in Figure 6. The tube 36 can then be mounted in this bracket, thebranches of which are eventually brought closer to the circumference ofthe tube, either hot or cold, so that they can adapt themselves to thediameter of the latter before being finally welded to the tube.

I claim:

1. The method of assembling a tube into a tube sheet which comprises;piercing a hole through the tube sheet from one side thereof; formingaround the hole a frustoconical tubular neck on the; opposite side ofthe plate that is of relatively greater height than the diameter of thehole; widening the bore. of said neck at its outer extremity andspreading the walls of the neck to form an inverted frustro-conical neckprojecting from the plate beyond the tube hole; heating said neck andsaid plate at its junction with said neck; introducing into theconvergent bore of the conical neck a punch of greater diameter thansaid hole and projecting said punch through said neck to a positionbeyond said one side of said plate to displace the material of said neckand plate adjacent said tube hole and thereby form a second neckprojecting from said one, side of said plate; heating both of saidnecks; seating the end portion of a tube in the cold state in both ofsaid necks, said tube having an external diameter fitting the bore ofsaid necks when the latter are heated and welding the distal endportions of said necks to the adjacent outer wall regions of said tube.

2. The method of assembling a tube into a tube sheet which comprises;piercing a hole through the tube sheet from, one side thereof forming anupstanding tubular neck on the opposite side of the plate that is ofsub- 4 stantially greater height than the diameter of the hole; wideningthe bore of said, neck, at its outer extremity and spreading the wallsof the neck to form an inverted conical bore in the neck converging tothe tube hole; heating said neck and said plate at its junction withsaid neck; introducing into the convergent bore of the neck a punch ofgreater diameter than said hole and projecting said punch through saidneck to a position beyond the opposite side of said plate to displacethe material of said neck and plate adjacent said tube hole therebyforming a second neck projecting from said one side of said plate;heating both of said necks; seating the end portion of a tube in thecold state in both of said necks, said tube having an external diameterapproximating that of the bore of said necks when the latter are heated;and welding the distal end portions of said necks to the adjacent outerwall regions of said tube.

References Cited in the file of this patent UNITED STATES PATENTS1,101,084 McCarty June 23, 1914 1,727,755 Dickinson Sept. 10, 19291,744,932 Swank Ian. 28, 1930 2,349,792 Rosenblad May 23, 1944

